Compared to applying cement mortar onto the wall manually, the plastering machine has the advantages of higher efficiency, time and labor saving, etc.
The existing plastering machine is generally provided with a set of upright rails. The set of upright rails is usually composed of two rails that are arranged uprightly and in parallel. The two rails are referred to as the left rail and the right rail respectively. Each of the left rail and the right rail is provided with a rack. The plastering machine head is provided with a driving gear. The plastering machine head can move up and down along the upright rails through the cooperation between the driving gear and the rack, such that the functions of a bottom-up plastering and a top-down press polish can be achieved.
However, the upright rails of the plastering machine have a fixed length. Since generally the story height of current residential building is about 3 meters, it is required that the length of the rails should also be about 3 meters. Nonetheless, usually the height of the doorway is only about 2 meters. Thus, the upright rails need to be tilted or disassembled to pass through the doorway, which is not convenient to a worker to do so and disassembling the upright rails greatly reduces the working efficiency.
For the above reasons, artisans in the industry have developed a plastering machine having adjustable upright rails. For example, a plastering machine having adjustable upright rails is disclosed in the patent document with the issuance No. CN 203755619 U. The upright rails of the plastering machine are adjustable and retractable. The plastering machine with the rails in a retracted status is very easy to pass through the doorway of a residential building. The use and operation of the plastering machine are very convenient. However, during the plastering process of the plastering machine, the first clamping piece of the plastering machine head needs to cover the resistant portion of the lever piece of the first resistant device to successfully pass through the first resistant device, so as to make the plastering machine head move from the first left rail piece to the third left rail piece. Even if the first clamping piece of the plastering machine head does not cover the resistant portion of the lever piece of the first resistant device, the plastering machine head will keep ascending to force the first clamping piece passing through the first resistant device. In that case, the first clamping piece and even the plastering machine head will be damaged. In addition, such type of plastering machine needs to be installed with an additional hydraulic cylinder as a transmission part of the upright rails, thereby increasing the manufacturing cost of the plastering machine.
Therefore, the plastering machine needs to be improved.